1. Field of the Invention.
The present invention relates to a radial seal, and more particularly, to a radial seal which provides a reasonable seal (not 100 percent) between a stationary windbox and a large diameter rotating cylinder, of a rotary kiln.
2. Related Art.
Radial seals are provided between a stationary windbox and large diameter rotating cylinder in rotating kiln devices. These radial seals are generally not employed for providing 100 percent air-tight seals. Rather, these seals are generally used as a barrier between hot air which surrounds the rotating cylinder and the cooler air existing in the environment in which the rotary kiln is operating. By providing a reasonable seal for preventing or hindering the escape of hot air from the vicinity of the rotating cylinder, a substantial amount of heat energy is conserved. Furthermore, by providing a barrier which inhibits air from escaping the rotary kiln device, such seals insure that enough air is maintained within the rotary kiln to allow combustion.
Known radial seals for use in rotary kilns include complex structures having several pads of heat resistant material (similar to brake shoes) mounted on spring devices. These pads are urged against the outer surface of the rotating cylinder of the rotary kiln by the force of the spring devices. The spring devices operate by compressing so as to allow the pads to conform to uneven cylinder surfaces and changes in the cylinder diameter. These known seals include relatively complex and expensive mechanical structures which are prone to mechanical malfunctions, are difficult to maintain and require complicated installation and replacement procedures. These known seals are problematic in many respects, primarily due to mechanical malfunctions arising from dirt and other particles which collect in the spring devices and between adjacent pads.